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Question
Extrusion of second polar body from egg occurs
Extrusion of second polar body from egg occurs
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Solution
The correct option is B after entry of sperm but before fertilization
Oogenesis is a type of gametogenesis during which a female gamete (ovum) is produced via multiple divisions. The site of oogenesis is ovary.
Primordial germ cells, also called oogonia (2n) firstly undergo mitosis to form diploid primary oocytes (2n).
The primary oocyte undergoes first meiotic division which gets arrested at prophase I of meiosis I till puberty.
The primary oocyte completes its first meiotic division and forms secondary oocyte and first polar body at puberty. The first polar body usually degenerates.
The secondary oocyte starts meiosis II which gets suspended at metaphase II.
When the sperm enters into the secondary oocyte, the secondary oocyte completes meiosis II to produce ovum (egg) and the second polar body.
Hence, the second polar body is formed after the entry of sperm but before fertilization. The polar body usually degenerates. Therefore, the extrusion of the second polar body from the egg occurs before fertilization.
The nucleus of egg (ovum) and the sperm nucleus fuse resulting in the formation of zygote. Zygote undergoes mitotic divisions called cleavage which result in the formation of an embryo.
Oogenesis is a type of gametogenesis during which a female gamete (ovum) is produced via multiple divisions. The site of oogenesis is ovary.
Primordial germ cells, also called oogonia (2n) firstly undergo mitosis to form diploid primary oocytes (2n).
The primary oocyte undergoes first meiotic division which gets arrested at prophase I of meiosis I till puberty.
The primary oocyte completes its first meiotic division and forms secondary oocyte and first polar body at puberty. The first polar body usually degenerates.
The secondary oocyte starts meiosis II which gets suspended at metaphase II.
When the sperm enters into the secondary oocyte, the secondary oocyte completes meiosis II to produce ovum (egg) and the second polar body.
Hence, the second polar body is formed after the entry of sperm but before fertilization. The polar body usually degenerates. Therefore, the extrusion of the second polar body from the egg occurs before fertilization.
The nucleus of egg (ovum) and the sperm nucleus fuse resulting in the formation of zygote. Zygote undergoes mitotic divisions called cleavage which result in the formation of an embryo.
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